Someone brought me an old 3GS stuck on 4.2.1 and with 05.15.04 baseband that needs to be unlocked. I know there used to be an option to do so with older versions of redsn0w, but I don't see that option in the current version. Does anyone have advice on the best way to do this today? I've already jailbroken and just need to get this baseband changed. About 4 hours of frustration so far.